Not exactly on-topic, but there are all kinds of sysadmins here, so Ithought I'd drop a line or two about CDs.

I backup stuff onto CDs all the time. My best programs, tools, data,photos, and whatnot I back up every 6 to 12 months from the last good copy.So, my good stuff can be 10th or 12th generation going back 10 or 12 years,but it's all readable.

But then there's the other stuff, the backups I did once for customerprojects, etc. Whenever I had to handle customer data I always made 2 CD orDVD backups of it in case during some operation I'd accidentally wipe adisk. Only happened once, so I'm glad I had the backups.

So, I'm going through boxes of the one-time backups ready to scratch thesurface or break the CDs in two before trashing them. No need to make themunreadable -- they're ALL unreadable! I was careful to put the CDs and DVDson the floor of my closet where they wouldn't be exposed to heat or light,which damages the dye used in recordable CDs. Well, not even the special"lasts a lifetime" gold-colored CDs survived. Mind you, these are CDs andDVDs I recorded once just as temporary backups; the latest in this batch isfrom 2007, so it's no great loss for me.

I guess this is a reminder for people who don't already know that recordableCDs and DVDs don't age well. And yes, I took a sampling of the CDs and ranthem on 3 different players, 2 of which are known to read just aboutanything. Can't track anything on any of them.

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Thank you for confirming most of my prejudices regarding CD-Rs andDVD-Rs.

More generally, I do not believe that archival storage methods areavailable at a price that is within reach of ordinary individuals.

My solution is "live" backups:

* I have all of my data on one peecee, on internal disk drives.

* I back up all of this data to multiple, USB-connected disk drives.

The USB-connected drives are my backup media. I don't expect them tofunction as archival storage. In particular, I rotate through them ina repeating pattern, with one media change every two weeks. My theoryis that the act of writing to the backup media serves to verify theircontinuing survival. The fact that I rotate through several media protectsme against even multiple hardware failures.

I haven't tried those, but the Navy did and ran some rather brutaltests:<http://site.produplicator.com/downloads/Manuals/China_Lake_Full_Report.pdf>Bottom line is:None of the Millenniata media suffered any data degradationat all. Every other brand tested showed large increases indata errors after the stress period. Many of the discs wereso damaged that they could not be recognized as DVDs by thedisc analyzer.

I've had more CD/DVD drive failures than media failures so I guess I'mthe exception to the rules.

So, out of 100 disks, how many were tested as readable at the end oftheir documented life span? What's that you say? 0? 0 out of 100,is a horrible number. Wake me up when that number is 1 or more outof 100.

Post by David KayeNot exactly on-topic, but there are all kinds of sysadmins here, so Ithought I'd drop a line or two about CDs.

snippo

Post by David KayeSo, I'm going through boxes of the one-time backups ready to scratch thesurface or break the CDs in two before trashing them. No need to make themunreadable -- they're ALL unreadable! I was careful to put the CDs and DVDson the floor of my closet where they wouldn't be exposed to heat or light,which damages the dye used in recordable CDs. Well, not even the special"lasts a lifetime" gold-colored CDs survived. Mind you, these are CDs andDVDs I recorded once just as temporary backups; the latest in this batch isfrom 2007, so it's no great loss for me.I guess this is a reminder for people who don't already know that recordableCDs and DVDs don't age well.

I'm sure there is some data storage sytem out there that can be putin a vault and read in the future, but I don't know what it is.

The only data recoding medium I know of that lasts is punched papertape.

"I guess this is a reminder for people who don't already know thatrecordableCDs and DVDs don't age well. And yes, I took a sampling of the CDs and ranthem on 3 different players, 2 of which are known to read just aboutanything. Can't track anything on any of them."

------------

This post was a bit alarming to me. And since I'm taking a day to rest afteroverexerting myself doing home repairs yesterday, I grabbed a sample ofCD-Rs that I burned in 2002 and tried to read them. I had five CDs handy ofthat vintage and all of them read just fine. They were all name brand disksand stored in individual envelopes in a home office environment. My CD-Rslook good thus far.

I see that you tried reading your old disks on different players. Did youburn those disks on several burners or did you use just one?

I found this article from 2012, in which the author tested 400 CDs burnedfrom '97 to '05 and was able to read all but 10 of them. The author thinksthat with more work he could read most of them too.

Post by Tak NakamotoI see that you tried reading your old disks on different players. Did youburn those disks on several burners or did you use just one?

Two different units, neither of which I have anymore. I don't remember thebrands but they were top-notch OEMs such as Toshiba. The CDs were Sony andVerbatim for the most part. The Verbatims had pre-applied labels which Iwrote on with Sharpies, so the Sharpie ink likely didn't penetrate below thelabel itself.

Thanks for the link. I have a more recent USB unit which I'll also try assoon as I find it.

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By the way, for my personal storage of data, programs I'm writing, music,photos, etc., I use two USB 3TB HD drives. I copy to one and then back itup to the other, so I have identical copies on each drive. My experiencewith HDs has been that with the exception of a little surface failure,generally the failures tend to be the motor or the stepper, usually thestepper. With stepper problems it's usually possible to eventually read thedisk; it just takes forever and often unplugging and replugging the drive tomove the stepper back to home position.

So, I'm thinking seriously of ditching CDs and DVDs entirely and backing upthe temporary stuff to external SSD (64GB) or the larger HDs. I think I'llget much better mileage from this method, and it'll be faster, too.

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Post by David KayeSo, I'm thinking seriously of ditching CDs and DVDs entirely and backing upthe temporary stuff to external SSD (64GB) or the larger HDs. I think I'llget much better mileage from this method, and it'll be faster, too.

You may want to reconsider the SSD idea:<http://www.pcworld.com/article/2921590/death-and-the-unplugged-ssd-how-much-you-really-need-to-worry-about-ssd-reliability.html>I haven't seen any such failures, yet.

Post by Jeff Liebermann<http://www.pcworld.com/article/2921590/death-and-the-unplugged-ssd-how-much-you-really-need-to-worry-about-ssd-reliability.html>I haven't seen any such failures, yet.

Oh I agree. As I said I'll be using SSDs for temporary storage, that iscustomer files that I need to transfer one place or another, in the same wayI used CDs and DVDs in the past. But for permanent storage I'm relying onconvential USB hard drives.

At first I was wary of the larger storage of 3TB drives. I had been quitecontent with 200 to 500GB, thinking that the all the extra bytes still haveto fit in the 2 1/2 inch HD physical profile. So, obviously they've got tomake the sectors way smaller. How small is too small? Will a 3TB HD be asreliable as a 500GB HD?

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Post by Jeff Liebermann<http://www.pcworld.com/article/2921590/death-and-the-unplugged-ssd-how-much-you-really-need-to-worry-about-ssd-reliability.html>I haven't seen any such failures, yet.

Oh I agree. As I said I'll be using SSDs for temporary storage, that iscustomer files that I need to transfer one place or another, in the same wayI used CDs and DVDs in the past. But for permanent storage I'm relying onconvential USB hard drives.

You may have missed the point of the article. The problem is thatwith no power applied and a warm SSD, the leakage currents increasesufficiently to affect long term reliability. One article claimedthat it's possible to loose data in about a month, if power is notapplied. There are also a few high reliability SSD packagers, thatinclude a battery. I'm suppose to be giving a talk on SSD to thelocal Linux user group next month and have accumulated a collection oflinks on the topic. I'll post a few when I return to my office toniteor tomorrow.

Post by David KayeAt first I was wary of the larger storage of 3TB drives. I had been quitecontent with 200 to 500GB, thinking that the all the extra bytes still haveto fit in the 2 1/2 inch HD physical profile. So, obviously they've got tomake the sectors way smaller. How small is too small? Will a 3TB HD be asreliable as a 500GB HD?

I have no idea. Reading data off a hard disk drive has been somewhatof a statistical exercise for at least 20 years. The days when youcan put an oscilloscope on the output of the head and actually see a"1" or "0" are long gone. These days, the waveform looks like garbageand the decision as to whether it's a "1" or "0" is an exercise indecompression, error correction, and probability.

"How NOT to evaluate hard disk reliability: Backblaze vs world+dog"<http://www.theregister.co.uk/2014/02/17/backblaze_how_not_to_evaluate_disk_reliability/>There are quite a few good links and insights in this article on drivereliability."Moral of the story: design for failure and buy the cheapestcomponents you can. :-)"Obviously, you're not running a server farm and will not be beatingthe drives to death. You're counting on the assumption that a lightlyused drive will last forever. That hasn't been my experience as I'vehad DOA drives pulled out of old stock when trying to fix a RAIDarray.

Drivel: Even pencil and paper are not reliable. More than one of mycustomers refuse to inscribe their passwords in a speadsheet, textfile, or suitable program. They write them on the smallest piece ofpaper they can find, using a pencil. The paper is then folded,spindled, and mutilated until the scribbles are unreadable. When itcomes time to login to some account, it can't be read. When I demandthat they transcribble the pencil scratches into a spreadsheet, theycan't read their own handwriting, and just stop. The one customerthat actually did transcribble the scribble pad, managed to get theupper/lower case letters all wrong. Last week, I had to use amicroscope and UV light in order to extract a password. I wouldn'thave mentioned this, except I have FOUR customers with exactly thesame bad habit. AAAAAAAAAAAAAAAAAAAAAAARGH!

Post by Tak Nakamoto"I guess this is a reminder for people who don't already know thatrecordableCDs and DVDs don't age well. And yes, I took a sampling of the CDs and ranthem on 3 different players, 2 of which are known to read just aboutanything. Can't track anything on any of them."------------This post was a bit alarming to me. And since I'm taking a day to rest afteroverexerting myself doing home repairs yesterday, I grabbed a sample ofCD-Rs that I burned in 2002 and tried to read them. I had five CDs handy ofthat vintage and all of them read just fine. They were all name brand disksand stored in individual envelopes in a home office environment. My CD-Rslook good thus far.I found this article from 2012, in which the author tested 400 CDs burnedfrom '97 to '05 and was able to read all but 10 of them. The author thinksthat with more work he could read most of them too.http://www.rlvision.com/blog/how-long-do-writable-cddvd-last-400-discs-put-to-the-test/

I find similar results with CDs and DVDs. I have CDsthat I burned in 2000 that still read fine. I stored them inplastic shoe boxes and kept them in a dry place. I also foundthat CDs stored in vinyl sleeves rather than paper seem to havefewer problems. The CDs that I found that didn't work were theCDs I didn't take care of, some of them were cheap and the topsurface just wore away. Some I would treat roughly and the topsurface got scratched. Others had tiny pinprick sized holes inthem but they read fine.

What probably helped my case was doing research. I gotinfo from professionals about what CDs were best for archivalpurposes. But the best solution for backup for people on abudget is to backup to enterprise class HDs then transfer to anew drive every two or three years. Most of these HDs have fiveyear warranties and if used minimally to store backups theyshould be fine for longer than three years. I just recommendevery few months powering up the drive for a few minutes. Theprices for enterprise drives have gone down greatly in the pastfew years too.

What probably helped my case was doing research. I got info fromprofessionals about what CDs were best for archival purposes.

Okay, WHICH CDs are best for archival purposes? Obviously Verbatim and Sonyaren't, given that I've lost so many. And again, I stored them away fromheat and light in an area that never gets above 70 degrees even on warmdays.

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What probably helped my case was doing research. I got info fromprofessionals about what CDs were best for archival purposes.

Okay, WHICH CDs are best for archival purposes? Obviously Verbatim and Sonyaren't, given that I've lost so many. And again, I stored them away fromheat and light in an area that never gets above 70 degrees even on warmdays.

Actually I would recommend you use DVDs rather than CDs. Ihaven't used CDs to store anything important since I switched toDVDs. Here is a guide that may help you.

http://www.digitalfaq.com/reviews/dvd-media.htm

If you want CDs I have heard that Taiyo Yuden are good. Ihaven't really done much thought about using CDs for archivinganything as they are less durable than DVDs. I've used VerbatimDVDs and Taiyo Yuden CDs without problems and the disks I burnedten years ago read fine in both cases. You should also make sureyou keep the disks in a dry place. Many of my disks were storedin a room where the temperature regularly reached 90 degrees soI don't think heat is that much of an issue. Dramatic tempchanges over a short period is a lot more damaging at leastthat's what I hear.

Post by David KayeI'd rather not archive on DVDs or CDs because they're simply too small. I'dprefer to store on something that's at least several hundred GB. That'sSSDs and HDs today.

Magneto-optical.

Uses a magnet to read, and a laser + magnet to write. Media looks likeold-school 3.5" floppies (until you look inside at least or you get thehigh-capacity 5.25" ones which then look similar but much larger).

Post by David KayeDVDs I recorded once just as temporary backups; the latest in this batch isfrom 2007, so it's no great loss for me.

I have CDs written in the late 90's that are still readable.I don't think I've ever had a CD failure.I had one CD/DVD drive that failed in a maddening way, but I don't thinkI've ever had media fail.I just tossed a copy of an MSDN Windows2000 CD, but it still worked, lasttime I tried, which was probably a year ago.I purged all of my Redhat CDs back to AS 2.1, but they have all been usedseveral times over the years.